Examples of imaging optical systems composed of mirrors are disclosed in U.S. Pat. No. 6,750,948 B2, US 2006/0232867 A1, EP 0 267 766 A2, U.S. Pat. No. 7,209,286 B2 and WO 2006/069 725 A1.
Because of a high reflection loss of the light on mirrors in such imaging optical systems, such systems can have transmission properties which cannot be tolerated when using EUV radiation, in particular with a wavelength which is less than 10 nm.